1. ADVERSE PROGNOSTIC FACTORS IMPACTING SURVIVAL IN RESECTED INVASIVE, MUCINOUS CYSTADENOCARCINOMAS OF THE PANCREAS Stephen J. Ko 1, Michele M. Corsini 2, Michael G. Haddock 2, Michael B. Wallace 3, Aminah Jatoi 5, George Kim 4, Leonard L. Gunderson 6, and Robert C. Miller 2 2 Department of Radiation Oncology and 5 Division of Medical Oncology, Mayo Clinic, Rochester, Minnesota; 4 Division of Medical Oncology and 3 Division of Gastroenterology, Mayo Clinic, Jacksonville, Florida; 6 Department of Radiation Oncology, Mayo Clinic, Scottsdale, Arizona; 1 Department of Radiation Oncology Mayo Clinic, Jacksonville, Florida BACKGROUND Although the prognosis for patients with resected invasive mucinous cystadenocarcinoma of the pancreas (MCP) is not well characterized, MCP is generally considered to have a more benign clinical course than that of pancreatic ductal adenocarcinoma. PURPOSE/OBJECTIVE To determine prognostic factors after definitive resection of invasive mucinous cystadenocarcinoma of the pancreas. (Table 1) CONCLUSIONS Patients undergoing resection of MCP with the presence of high grade histology (gr 3/4), involvement of lymph nodes and/or extension of tumor beyond the pancreas have a worse prognosis than once believed. Adjuvant therapy, similar to that prescribed to patients with non-mucinous invasive pancreatic malignancies, might be considered. Table 1. Clinical characteristics of 37 mucinous cystadenocarcinoma patients VariableNumber (%) T stage 18 (22) 221 (57) 37 (19) 41 (3) Grade 114 (38) 216 (43) 36 (16) 41 (3) N stage Positive5 (14) Negative30 (81) Not assessed2 (5) Extent of resection R033 (89) R13 (8) R21 (3) Treatment Surgery only28 (76) Adj radiation therapy only7 (19) Adj radiation therapy+ CT1 (3) Unknown1 (3) Systemic chemotherapy Yes1 (3) No35 (95) Unknown1 (3) Surgery type Whipple12 (32) Pylorus preserving5 (14) Total2 (5) Distal18 (49) Table 2. Association between survival time and N stage, grade, and T stage Table 3. Estimated median survival (years) according to N stage, grade, and T stage Median survival (years)95% CI N stage N013.3(7.6, 16.3) N10.8(0.5, NA)* Grade Grade 1-213.3(8.5, 16.3) Grade 3-42.4(0.5, 5.9) T stage Stage 1-214.1(8.5. 16.3) Stage 3-40.8(0.5, 5.6) Hazard ratio95% CIp-value N stage (1 vs. 0)8.9(1.4, 53.8)0.017 Grade (1 unit change)3.9(1.8, 8.4)< 0.001 Grade (3-4 vs 1-2)6.7(2.0, 22.2)0.002 T stage (1 unit change)3.6(1.7, 7.4)< 0.001 T stage (3-4 vs 1-2)13(3.4, 49.2)< 0.001 * The upper limit of this confidence interval was not estimable due to the distribution of censoring in this small subgroup. RESULTS Median follow-up was 4.1 years (0.06 – 16.3 year range), with 17 of 37 patients followed until death. Median survival for all patients was 12 years (95% CI 5.6 – 16.3). Adverse prognostic factors identified on univariate analysis included positive lymph node (median OS 0.8 vs. 13.3 years, p=0.017), grade 3/4 histology (median OS 2.4 vs. 13.3 years, p=0.002), and T3/T4 stage (median OS 0.8 vs. 14.1 years, p<0.001). (Tables 2 & 3) The five- year survival rate was 71%.